Shiroko
Swordsage 2/Rokugan Ninja 5/Shosuro Tejina 10/Rokugan Ninja +3
Feats: Able Learner [Human], Void Use, Karmic Twin [Scorpion Clan], Weapon Focus (Short Sword) [Sword Sage], Dark Stalker, Depths of the Void, Shadow Blade, Crippling Blow, Killing Blow, Untouchable, Gloom Razor
Final BAB: 16
Shosuro Tejina Casting: 10
Martial Initiate Level: 11
AEG, for instance, assumes it's perfectly OK to create a feat that can turn a PC into an NPC, or strip an NPC's powers completely away, if the target doesn't obey your commands... with a mere diplomacy check. Meanwhile, other things they publish amount to several pages of text and many die rolls to partially ignore hardness on objects you spend a long time lining up to strike. This is schizophrenic game development at best, and inept at worst. I would STRONGLY suggest ignoring any d20 mechanics from AEG, even as you should undoubtedly read their work for their fluff.
I don't remember what three of your feats actually do (Void Use basically gives SOME characters something more or less identical to AP, except it's AP you can recover between levels through roleplaying with no real costs (i.e. through performing the Tea Ceremony, IIRC), and Depths of the Void, I think, granted extra action points, but Crippling Blow, Killing Blow, and Untouchable are new to me). Likewise, I don't know what the Shosuro Tejina does, apart from apparently being a full base attack self-contained spellcaster. Without knowing its power in particular, I can't tell you what impact that will have on the character.
Most non-Cleric, non-Wizard based gishes are certainly not tier zero. That term is reserved pretty much exclusively for the spell-to-power erudite and POSSIBLY the Artificer if he has sufficient time to design and build all his toys. No gish can hit those levels with the things they give up to become gishes. Likewise, your initiator level is overrated in this build since all of your maneuvers will be first-level with that specific timing, and with the exception of Leading the Charge, Flame's Blessing (indirectly) and Burning Blade, no first-level maneuvers scale that well with level (as all of the others either don't scale or are capped).
I'm also detecting some HORRIBLE MAD here, even with Shadow Blade: Strength (for accuracy: you don't have Weapon Finesse), Dexterity (Damage through Shadow Blade (without TWF, which is a bit odd) as well as AC due to lack of armor and the other usual goodies), Con (most of those classes are d6 or d8 HD and you're in melee), Int (Initiative and Speed through Rokugan Ninja), Wisdom (AC through Swordsage), and whatever ability score governs your spellcasting. That's an awful lot of diversification; most Tier 1 classes are single-ability dependent to an extreme (i.e. wizards can be happy with Intelligence up the wazoo and any spare change directed to Constitution).
Unless there's something horribly horribly broken in those feats (it's AEG, you can never be sure), or in the class features or spellcasting of the Shosuro Tejina, I would probably say this fits in tier three, like most highly-optimized sneaky-types with options like martial maneuvers. If the spellcasting or class features are as broken as AEG's reputation, then I could see this MAYBE climbing to tier-2 equivalent, but that's unlikely.
(This sets aside the issue about using the tier system to evaluate characters - remember, the reason Tier Two is lower than Tier One is often because the Twos have as much raw power as a class as the Ones, but while any given One can access all of those options, any given Two cannot. For instance, despite using the same spell list, sorcerers are tier two because any given sorcerer can't access all the options available to sorcerers in general, while any given wizard can get damn closer simply by expanding his spellbook. I'm being a bit loose here.)
Crippling Blow allows me to sacrifice 1d6 of SA in order to deal 4 Dex damage. Killing Blow allows me to immediately kill anything that I drop to 5 hp or less using a sneak attack, no save. Untouchable grants me 50% concealment miss chance against all ranged attacks unless I am flat-footed.
The abilities that Shosuro Tejina gives me are a +4 bonus to spell DC when the target is flat-footed, Charisma Mod to AC, DR 15/crystal weapons, and SR equal to 15+Int Mod. It is a charisma based caster, which makes the character even more horribly MAD.
The only really thing even remotely overpowering is that two of the spells allow me to make copies of myself that I can switch places with as a free action. The lower level version (Shadow Twin) is just that, while the later one (Shadow Brother) can attack and make actions exactly like I can, however it cannot cast spells or speak.
I told the DM that being reliant on all six of my stats mitigates whatever powergaming could really be done with this character.
Well there's your problem: you're mixing AEG material with WotC material.
Just like to point out that when the d20/d10 oriental adventures stuff was printed out WotC owned (or the rights to the company or something wierd like that) AEG. The material in question is considered 2nd edition for the Legend of the Five Rings system which then got bought back by AEG for when they did 3rd Edition and 4th Edition L5R.
Now back to the original question I have to agree with Tempest that any time you mix Oriental Adventures and 3.5 D&D you can make some very interesting things happen. I will also have to agree with your DM that your character would be broken in ROKUGAN although not necesarilly in general. My advice toyour DM is not allow any of the 3.5 D&D books and just stick to the Oriental Adventure books (the secrets of series, Oreintal Adventures, Rokugan campaign setting, way of the ninja/samurai and creatures/magic of rokugan). This should keep all the characters "fair and balanced" within the system.
Well there's your problem: you're mixing AEG material with WotC material.
My advice toyour DM is not allow any of the 3.5 D&D books and just stick to the Oriental Adventure books (the secrets of series, Oreintal Adventures, Rokugan campaign setting, way of the ninja/samurai and creatures/magic of rokugan).
Alternatively, you could use the 3.5th books as normal - the is a Ninja in Complete Adventurer, and about seven verisions of the Samurai all over the place. I find Oriental Adventures itself, whilst 3.0th, is not too bad to make work with the other stuff (there are one or two wonky things, like being able to get Wild Shape and hence a lot of Druid PrCs with a one-level dip into Shapeshifter, but it is WotC). Also, Tome of Battle (whilst also known as Tome of Optimisation) *is* very orientally themed.
I think a plain Swordsage/(CAd) Ninja would be pretty nice, not terribly optimised but perfectly viable, especially with Weapon Finesse and Shadow Blade (Dex focus, Wis to AC - though it probably doesn't stack - and Ki, and anything spare in Con).
In the end, Shiroko turned out to be a fun and flavorful character that performed as well as I had hoped. My only real complaint was that I always spent my money on stat-boosting items
